Leakage resistance data acquisition system and data for maintenance of transmission line porcelain insulators along coasts in wet snow

The leakage resistance of transmission line insulators along coasts decreases with the accumulation of sea salt due to sea winds; particularly when relative humidity becomes higher and shed surfaces are slightly wet with rain or wet snow. In order to measure the real-time leakage resistance properties of a pilot string of 3 standard suspension porcelain insulator units and a pilot porcelain long-rod insulator which were automatically subjected to 100 V DC voltage, depending on the coast weather conditions, a leakage resistance data acquisition system managed by a personal computer is utilised. Three field test sites were built in December 1995 in an area in Rumoi subject to heavy sea salt contaminated area on the coast of the Sea of Japan. Estimates of insulation deterioration in working insulators for maintenance of transmission line insulators are based on these real-time measurements of pilot insulator leakage resistance and on weather data.